The invention relates to a zoom finder for varying magnification of the field view in association with an operation of varying magnification in a photographing lens system
Zoom finders for varying magnification of the field view in association with an operation of varying magnification in a zooming lens system are disclosed in Japanese Laid-open Patent 264034/87 (tokkai-sho 62-264034) or Japanese Laid-open Patent 159826/95 (tokkai-hei 07-159826). In Japanese Laid-open Patent 264034/87 (tokkai-sho 62-264034), a rotational movement of the photographic zooming lens barrel is transformed into a linear movement of the cam plate the direction of which is perpendicular to the optical axis of the photographic lens, i.e., in the film feeding direction, by using gear train and rack-and-pinion mechanism. The lenses of the finder optical system are moved by using the linear movement of the cam plate.
In Japanese Laid-open Patent 159826/95 (tokkai-hei07-159826), a rotational movement of the photographic zooming lens barrel is transformed into a rotational movement in horizontal plane of the cam plate by using gear train, which is adapted to move the lenses of the finder along the optical axis.
However, using gear train requires a large space in the camera and the cam plate movable in the film feeding direction requires more space to allow its movement, which cause the size of camera to increase. Furthermore, the directions between the movement of the cam plate and the one of lenses of the finder are different, which causes fair mechanical loss and requires more powerful motor and/or leads to much consumption of a battery to drive the motor.
The present invention is to provide a zoom finder which serves to make the size of camera compact and to reduce the mechanical loss in shifting the lenses to vary magnification of field view of the finder.
A zoom finder of the invention for varying magnification of field of view by shifting positions of a first lens and a second lens in a finder optical system comprises a moving member movable along an optical axis of the finder optical system in association with an operation of varying magnification in a photographing optical system; a first lever pivotally mounted on the moving member;
a first cam engaging the first lever to rotate it in association with movement of the moving member; a first supporting member for supporting the first lens movable along the optical axis of the finder optical system with engaging a slot formed in the first lever; a second lever of which one end portion is engaged with the moving member rotatable about the other end portion in association with the movement of the moving member; and a second supporting member for supporting the second lens movable along the optical axis of the finder optical system with engaging a cam slot formed in the second lever; wherein the first lens is shifted by the rotation and the movement along the optical axis of the finder optical system of the first lever and simultaneously the second lens is shifted by the rotation of the second lever, which are caused in association with the movement of the moving member.
A zoom finder of the invention, installed in a camera including a variable magnification lens barrel movable from a retracted position where the lens barrel is fully retracted inside body of the camera to a variable magnification section where a photographing optical system is adapted to have a variable magnification by moving the lens barrel back and forth, capable of varying magnification of field of view by shifting a first lens and a second lens in a finder optical system in association with movement of the variable magnification lens barrel, comprises a moving member guided to move by a guiding means disposed along an optical axis of the finder optical system and interlocked with the variable magnification lens barrel via an interlocking mechanism so as to be able to automatically move in association with movement of the variable magnification lens barrel in the variable magnification section; a first lever pivotally mounted on the moving member; a first cam engaging the first lever to rotate it in association with movement of the moving member; a first supporting member for supporting the first lens movable along the optical axis of the finder optical system with engaging a slot formed in the first lever; a second lever of which one end portion is engaged with the moving member rotatable about the other end portion in association with the movement of the moving member; and
a second supporting member for supporting the second lens movable along the optical axis of the finder optical system with engaging a cam slot formed in the second lever; wherein the first lens is shifted by both the rotation and the movement of the first lever and simultaneously the second lens is shifted by the rotation of the second lever, which are caused in association with the movement of the moving member, and the interlocking mechanism is disabled with its interlocking function when the variable magnification lens barrel moves into the retracted position from the variable magnification section.
As the guiding means of the zoom finder of the invention, a guiding slot can be applied, the length of which is limited to the one corresponding to a length of region where the lens barrel can be moved to vary magnification.
As a part of the interlocking mechanism of the invention, a resilient member is used, which can disable the interlocking function of the interlocking mechanism by absorbing a shift of the lens barrel when the lens barrel moves into the retracted position from the variable magnification section.